/*
* DATATYPES:
*
* 0. Javascript can accomodate different types of data in primitive and complex forms.  When declaring
* a variable, it is not necessary to declare a datatype.  The type of variable will be automatically
* determined during program execution.
*
* 1. Primitive types utilize physical memory in that, each value is stored within the 8 bytes allocated
* for each variable.
*
* 2. Complex types are not stored in memory directly.  Since they do not have a fixed size, only the
* reference to the value is stored in each variable.
*/

/*
* PRIMITIVE DATATYPES
*/
// Number
var a = 25.4;   // can include decimals
var b = 123e-5; // scientific notation used for larger numbers

// String
var c = "Sample string of characters!";  // a sequence of characters enclosed in quotations

// Boolean
var d = true;   // can be one of two states: true or false
var e = false;

// Undefined
var f;          // When a variable is declared without a value, the default value is 'undefined'.
console.log(f);

// Null
var g = null;   // Null means "nothing".  The Value is null, but the type is considered an object.

// NaN
var h = NaN;    // "Not a number" is still considered a 'number' type despite its name.  NaN is returned
console.log("pete"/5);    // when something cannot be converted in to a number type.

// Infinity
// As in mathematics, any division by zero will result in an "infinity" type.
// If the dividend is a negative number, the operation will result in "-infinity"
var i = -5/0;
console.log(i);

/*
* COMPLEX DATATYPES
*/
// Array
// A sequence of values enclosed in square brackets and separated by commas.  Each value has an index
// which is '0' for the first value in the array.
//
var j = [4, 6, 30, 9, 80];   // the variable 'k' stores the reference to the memory location for the array
var k = ["Frank", "Jerry", "Kim"];  // each value can be accessed using l[index]
console.log(j[3]);                  // prints the 4TH value in array 'k'.

// Object
// Similar to array, but instead of a sequence of single values, an object is a sequence of
// 'name':'value' pairs.  Instead of an index, the values are accessd by their corresponding 'name'.
//
var l = {
  id: 42,
  color: "gray",
  type: "laminated",
};
console.log(l.color);      // prints "gray"

// Function
// A section of code that can be re-used and called upon if needed.  Using functions is a 2 step
// process: Declaration and Execution.  Values can be 'passed' to the function using parameters in the
// funciton declaration.  We can call a funciton many times without having to write the same code
// over and over
//
function test(number) {                // Declaration
  console.log("Testing " + number);
}
test(5);                               // Execution - Prints "Testing 5"